Method of laying carpet to avoid seam peaking and apparatus therefor

ABSTRACT

A method of laying carpet to avoid seam peaking, the method employing an enhanced width seaming tape spanning the abutting edges of the carpet forming the seam. The tape has a hot melt adhesive on the upper surface facing the carpet backing. An enhanced width carpet seaming iron is employed to melt the adhesive and to provide a bond between the tape and the carpet backing. In an alternative embodiment, the tape is made in three segments with one of them applied spanning the seam and the other two in flanking positions along either side of the seam spanning tape. In another embodiment the seaming tape is constructed with a composite modulus of elasticity which varies across the width of the tape. The invention also includes several embodiments of the enhanced width seaming iron for application of the tape to the carpet seam.

CROSS REFERENCE TO RELATED APPLICATION

This is a Continuation-In-Part of patent application Ser. No. 819,804,filed on Jan. 16, 1986, now Pat. No. 4,749,433.

FIELD OF THE INVENTION

This invention relates generally to carpet seaming and more particularlyto a method and apparatus for laying carpet with seams so as to reduceseam peaking.

DISCUSSION OF THE PRIOR ART

It is well known to join two pieces of carpet over conventional padding,by means of a heat-activated adhesive tape disposed along the seam.Carpet seaming tape has disposed on its upper surface hot melt adhesivematerial which melts when heat is applied. While the adhesive still isin the molten state, two pieces of carpet can be joined along the tapeto create a seam. The hot adhesive cools and hardens very quickly.

The means which has commonly been used to heat the tape joining carpetsections together is typically a hand-operated electric iron, usuallyhaving a rectangular and substantially flat base. The iron is movedlongitudinally along the adhesive tape causing the adhesive to melt,whereupon the sections of carpet are pressed down on the tape.

Two seaming procedures are in common usage. The first, referred to asbackseaming, involves inverting the carpet and applying inverted tape tothe joint with the application of heat and pressure on the back side ofthe tape. The second and more popular procedure, known as face seaming,involves working from the face of the carpet with the edges thereofcentered over a face-up strip of tape having a ribbon of hot-meltedadhesive thereon. The seaming iron is inserted between the upturnededges of the carpet to melt the adhesive, following which the carpetedges are immediately pressed into place to form a permanent bond.

One of the problems which is common when carpet is laid is theoccurrence of seam "peaking." A peaked seam is one in which the edges ofthe carpet at the seam form a ridge. Peaking seams occur primarily onhigh end, heavyweight carpet with smooth texture. When this tendency iscombined with the fact that people who have such carpeting installed aretypically more critical those who buy less expensive, rougher texturedcarpets, it is quickly apparent that seam peaking is a problem of someimportance.

It is commonly thought in the carpet industry that there are severalcriteria which are normally necessary for this problem to occur. One istoo much or too high heat generated by the seaming iron, and the otheris such high heat combined with a carpet having a thick, dense pile. Thetheory goes that the heavy pile forms an efficient layer of insulationabove the seam, trapping the heat for several minutes. The theorycontinues to the effect that the excessive temperature causes thepolypropylene primary backing to shrink very slightly, while the latexadhesive and jute secondary backing are unaffected. The theory is thatthis action causes the edge of the carpet to curl upwardly veryslightly, forming the peak, unimpeded by the seaming tapes. When thisoccurs, no amount of stretching will flatten these seams because thedistortion of the backing is permanent.

The fact that the seam peaking problem is very real is evidenced fromattemps by carpet manufacturers and seaming iron manufacturers topropose solutions, some of which may help but do not appear to havesolved the problem. Economic necessity in recent years has forcedinstallers to handle more square yards of carpet per day. As a result,temperatures used in seaming irons have increased with the need forfaster seaming.

One theory for solving the recognized problem is that several stepsshould be taken. The first is to reduce the seaming iron temperature toa level which will completely melt the adhesive on the tape at a minimumworkable rate. A tape which has adhesive thereon which will melt at thelowest possible heat setting on the iron, while allowing a work rate ofseveral feet per minute, is preferable. A scrap of carpet several feetlong and slightly wider than the tape, placed face down under the tapewill give a firm foundation and prevent the carpet from adhering to thepad. Some installers have used a board or strip of linoleum for thispurpose with at least somewhat positive results. Some installers haveused a tool box on top of the seam to hold it in place and that,according to one manufacturer, contributes to the problem. Heat andmoisture are trapped underneath the tool box, increasing the possibilityof seam peaking and color change at the seam. That manufacturerrecommends an unweighted three-foot piece of wood 2×4 for this purpose.It provides sufficient weight while allowing heat to escape along theedges. Even better, according to this attempted solution of the peakingproblem, is a steel straightedge drilled full of holes to allow heat andmoisture to escape. This manufacturer does not state that these stepswill solve the problem but states that it should result in fewercustomer complaints and reduce the calls to rework while admitting thatthere may be other causes of peaked seams and other possible solutionsfor these causes.

A seaming iron manufacturer has promoted a seaming iron which does themelting job with a lower temperature setting, purportedly to helpeliminate seam peaking.

Other suggestions for solving the problem include creating a matchingserpentine abutting carpet edge but this was not found to be practicalwhen put into practice. Another attempted solution is to form a groovedsole plate on the seaming iron to guide additional adhesive to themiddle between the edges of the carpet, but this did not solve theproblem.

Others have used thicker, heavier seaming tape in place of or inaddition to placing heat absorbing materials under the seam in order toattempt to counteract the seam peaking problem.

It has been found that when the guidelines for reducing peaking as setout above were followed, the problem may be somewhat reduced in someinstances but it was not solved. It thus appears that heat within normalranges is not the source of the problem, except when the seaming iron issubstantially too hot. In general, the existence of the problem has beenswept under the rug and the proposed solutions are at best stop gapattempts to reduce complaints.

One carpet manufacturer, in an extreme measure to attempt to resolve thepeaking problem, has made plans to produce wider carpet to reduce thenumber of seams necessary. This 13.5 foot wide carpet will definitelyreduce the number of seams but it will not prevent them in any room thatis more than 13.5 feet in both directions. Also, this size carpetingwill be very difficult to handle.

SUMMARY OF THE DRAWING

Careful observations of the carpet seam peaking situation have resultedin new directions for analyzing and solving the problem as disclosedherein. Not all carpet layers work with a seaming iron at too high of atemperature but the peaking problem still exists. A very significantfinding was that, in actual practice, peaking did not necessarily resultafter the seam was created and the heated surfaces had cooled, butoccurred after the carpet had been stretched into position on the floor.

Not only does peaking not normally occur until after stretching, thegreater the tension put on the carpet, the greater are the chances ofpeaking occurring or the higher the peak tends to be.

Broadly speaking, according to this invention the solution to theproblem of carpet seam peaking is to employ a hot-melt coated seamingtape having a width generally about two to three times that of normalseaming tape, or even wider. Alternatively, three normal width seamingtapes can be used in a flanking arrangement. Another alternative is touse a seaming tape which is constructed so as to have a compositemodulus of elasticity which varies across the width of the tape. Whenapplied in a conventional face seaming manner, the problem of peaking issubstantially reduced or eliminated.

The invention also concerns several embodiments of extended widthseaming irons for use with the extended width seaming tape. Oneembodiment uses an adapter plate secured to a conventional iron. Anotheris comprised of two separable halves to facilitate removal at the end ofa seam. Still another embodiment comprises an expandable and retractablewidth iron.

BRIEF DESCRIPTION OF THE DRAWING

The objects, advantages and features of this invention will be moreclearly perceived from the following detailed description, taken inconjunction with the accompanying drawing, in which:

FIG. 1 is an exaggerated sectional representation of the prior artproblem which this invention solves;

FIG. 2 is a somewhat simplified section through a portion of a typicalsegment of carpet;

FIG. 3 is another sectional view showing the forces involved in laying,seaming and stretching a carpet, depicting the origin of the seampeaking problem;

FIG. 4 is an exaggerated view of the result of the peaking problem, thesource of which was shown in FIG. 3;

FIG. 5 is a cross-sectional representation of the solution to the seampeaking problem of this invention;

FIG. 6 is an enlarged sectional view similar to FIG. 1, showing thesolution resulting from employing one embodiment of this invention;

FIG. 7 is a sectional view similar to FIG. 6 showing the solutionresulting from employing an alternative embodiment of the invention;

FIGS. 8A-D schematically show different conditions of deformableelements;

FIGS. 9A-D schematically show conditions similar to FIGS. 8A-D withdifferent elements;

FIGS. 10A-C schematically show theoretical conditions of carpetdeformation adjacent to a seam;

FIG. 11 shows in exaggerated form the effect of employing the extrawidth tape of the invention at a seam;

FIG. 12 is one embodiment of an enhanced width carpet seaming iron ofthe type shown in FIG. 5;

FIG. 13 is a side view of the seaming iron of FIG. 12;

FIG. 14 is an enlarged, partial view of the spring clamp employed tointerconnect the adaptor plate and seaming iron of FIG. 12;

FIG. 15 is a side view of an alternative embodiment of the carpetseaming iron of FIG. 5;

FIG. 16 is a top view of the carpet seaming iron of FIG. 15;

FIG. 17 is an end view of the iron of FIG. 15;

FIG. 18 is a side view of another alternative embodiment of the carpetseaming iron of FIG. 5;

FIG. 19 is a top view of the iron of FIG. 18;

FIG. 20 is an end view of the carpet seaming tool of FIG. 18 in open orexpanded position;

FIG. 21 is an end view similar to FIG. 20 showing the iron in closed orcontracted position;

FIG. 22 is a cross section through a seamed portion of carpet, employingthe present invention before stretching the carpet for finalinstallation;

FIGS. 23-26 show stretching loads of specific enlarged sectionalsegments of the carpet of FIG. 22;

FIG. 27 illustrates in exaggerated manner the stretched configuration ofthe carpet of FIG. 22 incorporating the stretching loads depicted inFIGS. 23-26;

FIG. 28 is a plan view of another embodiment of seaming tape havinglateral modulus of elasticity variations in accordance with theinvention;

FIG. 29 is a plan view similar to FIG. 28 showing another embodiment ofseaming tape;

FIG. 30 is a plan view similar to FIG. 28 showing still another seamingtape embodiment, and

FIG. 31 is a plan view similar to FIG. 28 showing yet another seamingtape embodiment.

DESCRIPTION OF A PREFERRED EMBODIMENTS

With reference now to the drawing, and more particularly to FIGS. 1through 4 thereof, the basis for the problem which this invention isdesigned to correct is portrayed. FIG. 1 is a relatively simple, albeitexaggerated, representation of the current seam peaking problem asfinally manifested when the carpet laying team has departed. Floor 11 iscovered with a conventional resilient pad 12 and carpet sections 13 and14 are laid on top thereof. The problem to which this invention isaddressed is represented by seam 15 which, in this figure, has raisedfrom the pad, resulting in a peak along the length of the seam and aV-shaped gap between the carpet tufts. As stated previously, thispeaking problem only occurs after the carpet has been laid. Seaming tape16, normally about three inches (7.62 cm) wide, has been applied tosecure the two carpet elements together at the seam and the carpet hasbeen stretched and secured at the edges of the room. It is this peakingproblem and the solution thereto to which this invention is addressed.The construction of seaming tape normally includes glass fibers,commonly referred to as scrim, so it is very resistant to stretching.

A detail of the typical carpet construction is shown in FIG. 2. Theloops or carpet tufts 21 pass through primary backing 22 and are securedthereto by a latex tuft binding material 23. Finally, secondary backing24 is placed over the latex binding and the bight portion of theU-shaped tufted elements as shown in the drawing.

The primary backing is normally a synthetic fabric made in a fine ordense weave to facilitate the insertion of the tufting material. Thesecondary backing is normally of a different weave (less dense) than theprimary backing material and may be a natural material such as jute orit may be a synthetic material. One of the sources of the peakingproblem is that the primary and secondary backings have differentstretching characteristics, that is, their moduli of elasticity differ.

When the stretching forces are applied to the carpet as shown in FIG. 3,there is an unequal stretching in that the secondary backing tends tostretch more easily. The carpet is anchored at one side of the room anda stretching tool or machine is applied to the edge of the carpetadjacent the other side of the room. The carpet is forcefully stretchedtoward that wall in the direction of arrow 25. The force or load line 26is shown centered, parallel to stretching force line 25. As wouldnormally be expected, the forces are distributed throughout thethickness of the carpet so that the resulting load line would be nearthe center. However, from FIGS. 3 and 4 it can be seen that the onlyconnection between the load line in carpet section 27 and carpet section28 is through seaming tape 31. Therefore, the load line will have todivert from its straight or parallel direction and pass through seamingtape 31. This means that the secondary backing is secured at eitherfloor extremity and the only connection between carpet sections is madeat the bottom surface of the secondary backing. Since the stretchingload distributed throughout the carpet from one wall to the other wouldwant to remain parallel, the seam would have to rise as shown in FIG. 4so that the load line can become as straight as possible. This couldeasily be demonstrated by folding a piece of paper and then pulling awayfrom the fold on either end. The downward pointing peak of the foldwould tend to rise to become as straight as possible. The phenomenondescribed above is referred to herein as load realignment.

The effect shown in FIG. 4 is contributed to by the fact that thesecondary backing tends to stretch more easily than the primary backing.This condition may be referred to as snap-back. The extra stiffness ofthe primary backing tends to cause an internal tension in each sectionof the carpet which, because the secondary backing stretches moreeasily, would tend to cause an upward curl after the seam is formed andthe carpet has been stretched. The only reason that the upward curlcannot mature into full bloom is because the ends are secured either tothe tack strips at the periphery of the room or to another piece ofcarpet at the seam by means of the seaming tape.

Thus, there are two contributing but related factors which tend to causeand exacerbate the peaking problem as shown in FIG. 1. Because normalcarpet seaming tape overlaps the seam by about 11/2 inches on eitherside, the two factors are physically coincident and are additive, eachincreasing the effect of the other.

The problem is solved, or at the very least, substantially reduced, bythe method and apparatus shown in FIGS. 5-7. Seaming tape 35 shown hereis between two and three times the width of the conventional seamingtape shown in FIGS. 3 and 4. Thus, a greater portion of the secondarybacking of carpet sections 36 and 37 are secured to the seaming tape.The seaming iron, or sadiron, employed for applying this tape to formthe desired seam is represented by reference numeral 38. It can have anumber of embodiments as will be discussed later herein. It has beenfound that by increasing the width of seaming tape and consequentlyincreasing the proportion of the secondary backing which is secured bythe tape at the seams, the peaking problem is eliminated orsubstantially reduced. It is important to note that at the seam, onlythe bottom or secondary backing is subject to stretching forces, andthese stretching forces are, of course, transmitted from the secondarybacking through the adhesive to the seaming tape and back through theadhesive to the secondary backing on the adjacent section of carpet.

The following is a simplified explanation of snap-back and loadrealignment phenomena and how their effect in creating the carpet seampeaking problem is greatly reduced by the practice of the presentinvention. There are two basic reasons why peaking is no longer visiblewhen the teachings of this invention are employed. The first is that thesnap-back condition is substantially reduced. Secondly although the loadrealignment phenomenon is not eliminated, it is removed far enough fromthe seam so that the effects of snap-back and load realignment areindependent and not additive. The result is that seam peaking is greatlydiminished, to the point of being insignificant under nearly allcircumstances.

The basic reason that the carpet at the seam does not snap back as muchwhen the increased width tape is employed is that the tape, normallyincluding glass fibers which are highly resistant to deformation,functions as reinforcement for the bottom layer of the carpet. Thisresults in the creation of an area of the carpet where snap back isreduced because there is less relative motion between the primary andsecondary backings.

For simplification purposes, analogies will be used in the followingword pictures and drawing figures. Reference will be made to FIGS. 8-11in explaining the theory of carpet seam peaking and its solution bymeans of this invention.

Assume the top and bottom backing of the carpet are rubber bands 111 and112 respectively, with no latex binding material between them. They areshown in FIG. 8A as having substantially the same elasticity, inunstretched condition. Then, assuming they are subject to equalstretching forces represented by arrows 113A and 113B, they are deformedequally as shown in FIG. 8B. These rubber bands represent the top andbottom carpet backing layers. If the top rubber band, or top carpetbacking, is released, it snaps back to its original position, asrepresented by FIG. 8C. Now assume that a substance such as latex core114 is inserted between the bands 111 and 112 before the top one isreleased. FIG. 8D shows that when band 111 is released, it does notreturn all the way back to its original position. The latex corepresents a shear resistance to top layer 111 snapping all the way back.As employed here, shear resistance is the amount of resistance thatexists to relative movement between the top and bottom bands 111 and112, or between the top and bottom carpet backings.

The conditions are changed somewhat in FIGS. 9A-D. Band 118 is the sameas band 111, but bottom band 115 is much stiffer or resistant todeformation, preferably about an order of magnitude stiffer than bottomband 112. This represents the difference between the top carpet backing,typically polypropylene, and the glass fiber based seaming tape. Thusthese bands represent the top carpet backing and a bottom backingequivalent to seaming tape in stiffness, or resistance to strain. Ifforces 116 and 117 are applied to bands 118 and 115 in order to achievethe same deformation, force 117 would be greater, by nine to ten timesfor example, than force 116. This would result in a total stretch ofabout 25% of that of FIG. 8B for the same total force applied. As inFIG. 8C, release of band 118 in FIG. 9C allows it to snap back to itsoriginal position. But it would only snap back about one-fourth as faras before because it was not stretched as far. Like FIG. 8D, FIG. 9Dshows that latex core 121 adds shear resistance to prevent band 118 fromsnapping back even that far, so that force 116A is distributedthroughout the latex core. Thus band 118 might snap back only aboutone-eighth as far as did band 111 in FIG. 8C.

Now the theoretical aspects will be carried farther in FIGS. 10A-C.Assume right hand end 122 of a carpet segment is one side of a seam. Thecarpet segment is formed of backing or band 118 on top and backing 115on the bottom with latex 121 therebetween, equivalent to FIG. 9D.Immediately to the left is another segment of carpet comprised of bands111 and 112, with latex 114 between them, equivalent to FIG. 8D. Theseare contiguous elements and are shown separated for illustration only,to provide examples of how different carpet segments would behave ifthey were isolated. This indicates that if the two segments were buttedand secured, the top portions would not meet. However, reality is thatthey do meet and FIG. 10B depicts that condition. Because of theresilience or shear force of contiguous latex layer 123, top 111 tendsto be pulled to the right and top 118 tends to be pulled to the left andthe adjacent ends would meet at a location intermediate their respectivepositions in FIG. 10A. At what specific intermediate position is afunction of the amount of shear resistance produced by pulling top 118to the left. How much relative motion there is at seam end 122 is afunction of how much latex 123 there is between the two layers orbackings. That is one reason why peaking is more of a problem withthicker carpets. Because of this snap-back adjacent the seam, wherebacking 118 is not secured at right-end 124, it is easily seen how anupward curl would result at the seam. Top layer 118, through latex core123, is pulling up on the right end 122 of bottom layer 115, which isactually the only connection across the seam, indicated by force arrow125.

An increase in latex thickness results in reduced shear resistance,while the length of band 115 (width of seaming tape) increases shearresistance. The longer band 115, the more shear force that can safely begenerated with the top layer without causing peaking. If band 115 isthought of as reinforcement to the carpet secondary backing, adifference in that reinforcement width by a factor of two results intwice the shear resistance and about half the amount of peaking causedby snap-back. An example is shown in FIG. 10C with reinforcing area 126twice as wide as layer 115. A positive result, because of increasedshear resistance between bottom backing 126 and top backing 127, is thatright hand end 131 of backing 127 is only half as far from seam end 122as it was in FIG. 10B, so that snap-back peaking is only half of what itwould have been in FIG. 10B. Force arrow 132 represents the fact thatthe stretching forces on the carpet are connected across the seam at thebottom.

Finally, load realignment is represented in FIG. 11. Wide carpet seamingtape 133 extends across the seam and force arrow 134 represents the factthat the stretching forces cross the seam only through the tape. Thisresults in an actual lifting of the carpet in the vicinity of the seam(see FIGS. 6 and 7) so that the load line can be as straight aspossible. To reiterate, the forces 134B and 135B at the wall aresubstantially equal, making resultant load line 136 centered in the leftportion. That load line tries to stay horizontal through seaming tape133 at the seam, causing the lifting force to result. When that liftingforce is removed a reasonable distance from the seam, its effect on theseam itself is substantially nullified. Conversely, the narrower theseaming tape, typically about 1.5 inches (38.1 mm) on either side of theseam, the closer is the load realignment to the seam. When the liftingforce and the seam line up, the load realignment effect and thesnap-back effect reinforce each other. Even without snap-back, loadrealignment near the seam would tend to create a peaking problem.

To summarize this analysis of the problem and the solution, FIG. 1 showsthe problem of snap-back and load realignment combining to accentuatethese two carpet peaking causes. The solution to both causes of thepeaking problem is the enhanced width tape shown in FIGS. 5-7. The seamin FIG. 6 shows little or no peaking because of reduced snap-back, andrelocation of the load realignment to a place far enough removed fromthe center of the seam to ensure that it does not combine with thesnap-back effect. The ideal width of the seaming tape to achieve thedesired results ranges from about one and one-half normal width toseveral times that width. In theory, the wider the better, but cost andhandling ease limit the practical width to about six inches. The minimumwidth of the tape to achieve satisfactory improvement of seams dependson several factors, including thickness of the latex core, as mentionedabove. Thus, each carpet has its own ideal tape width, but it should besubstantially wider than what has heretofore been normal.

Experimentation has shown that three conventional width seaming tapes inparallel, with one of them (39) being in the normal position centered atthe seam and the other two (40, 41) flanking the central tape, can alsosubstantially reduce seam peaking. Interestingly enough, this is trueeven if the flanking tapes are not secured directly to the center tape,as shown in FIG. 7. The reduction of the stretching allowed in thesecondary backing is just as true of this alternative configuration. Ineither case, the linear, lateral proportion of the secondary backingwhich is allowed its normal stretching characteristics is reduced byeither of these embodiments because the seaming tape stretchessubstantially less than does the secondary backing of the carpet. Bybeing substantially rigid, the tendency of the secondary backing tostretch more easily, causing the two joined carpet pieces to curlupwardly as discussed above, is greatly reduced.

The basic invention using enhanced width seaming tape to obviate thecarpet seam peaking problem has been described above. A furtherrefinement of the invention, wherein the tape structure itself ismodified, in addition to having enhanced width, will now be discussedwith respect to FIGS. 22-31. The tape has been modified by variousstructural embodiments, so that the modulus of elasticity varieslaterally across the tape.

The effect and usefulness of varying the modulus of elasticity acrossthe width of the seaming tape are illustrated in FIGS. 22-27. A portionof unstretched seamed carpet divided into segments is shownschematically in FIG. 22 and the segments are shown in more detail inFIGS. 23-26.

Segment 201 of FIG. 22 is represented in FIG. 23. The carpet tufts, orface yarns 202, are tufted into primary backing 203 and are held inplace by latex layer 204 which is in turn covered and secured tosecondary backing 205. Assuming that the modulus of elasticity ofprimary backing 203 is about twice that of secondary backing 205, thevertical location of resultant stretching force 206 would be abovecenter so that distance 208 would be about twice that of distance 207.

The stretching forces on segment 209 are shown in FIG. 24. The outeredge 210 of the seaming tape comes into play. The modulus of elasticityof this lateral segment of tape is lower than the modulus closer to thetape center. Assuming the modulus of elasticity of seaming tape portion210 in carpet segment 209 is about one-half the modulus of primarybacking 203, the composite modulus of this portion of the seaming tapetogether with secondary backing 205 would approximately equal that ofthe primary backing. In this instance resultant stretching force 211 isvertically positioned so that distances 212 and 213 are about equal.

Carpet segment 214, shown in FIG. 25, includes a portion of centersection 215 of the seaming tape. This center section is configured tohave a higher modulus of elasticity than does that portion included incarpet segment 209. Assuming the modulus of elasticity of tape portion215 is about one and one-half times that of primary backing 203, thecomposite modulus of the seaming tape and secondary backing 205 would beabout twice that of the primary backing. This would provide resultantstretching force 216 vertically located so that distance 217 is abouttwice distance 218.

Carpet section 219 (FIG. 26) is that which abuts the seam and includesanother portion of center section 215 of the tape. Because the carpetbackings are discontinuous at abutting edge 221, resultant stretchingforce 220 is vertically located in alignment with the center of seamingtape 215.

Note the right and left stretching load arrows in FIGS. 24-26, where theright arrow is lower than the left in each figure. This progression ofvertical locations of the resultant stretching forces is shown in FIG.27 as a combination where all the load lines are aligned resulting instraight composite line 222. This is a schematic and exaggeratedrepresentation created when the seamed carpet is stretched during thefinal installation process.

While the FIG. 27 representation indicates a substantial rise at theseam, in actuality the distributed load forces result in an undetectablyslight rise at the seam which could not be termed a peak. Thus theenhanced width, laterally varied modulus tape provides the same but aneven more effective solution to the peaking problem than is provided bythe basic invention of FIGS. 5-7.

There are several different ways to construct seaming tape such that themodulus of elasticity varies transversely across the width of the tape.Examples of such tape construction are illustrated in FIGS. 28-31.

The seaming tape construction shown in FIG. 28 comprises a typicalsubstrate or paper barrier 223, hot melt adhesive layer 224 and fibersformed as specially knitted scrim 225. The fibers are typically glassfibers, having a very high modulus of elasticity. As configured, outeredge margins 226 of the scrim contain fewer yarn elements per linearsegment than does center section 227. With this structure, the compositemodulus of elasticity of the center section would be about twice that ofouter marginal areas 226. As can be appreciated many other modulusrelationships would be possible using the scrim arrangement of FIG. 28.

Another scrim configuration is shown in FIG. 29, comprised of paperbarrier 228, hot melt adhesive layer 229, central scrim 230 and flankingmargin scrims 231. By varying the type of material and scrim spacingused in outer edge margin areas 232 and central section 233, thevariation in the composite modulus across the width of the tape can befine tuned to smooth the shape of the seam when the laid carpet isstretched.

Another seaming tape construction is shown in FIG. 30. Paper barrier 234has hot melt adhesive layer 235 and two superimposed scrims, namelyknitted type 236 and straight type 237. As in the FIG. 29 configuration,the choice of materials and spacing can be varied to custom tailor theratio of the modulus of elasticity between outer edge margins 238 andcentral section 239.

Three areas of differing composite modulus of elasticity are depicted inFIG. 31. Paper barrier 240 holds adhesive 241 and scrims 242, 243 and244 having different lateral lengths of scrim elements. These yieldthree distinctly different moduli in outer margin areas 245,intermediate flanking areas 246 and central section 247.

From these examples it is likely that many more scrim configurationscould be devised using the teachings herein.

Examples of apparatus suitable for heating the hot melt adhesive on theenhanced width seaming tape, represented schematically by sadiron 38 inFIG. 5, are shown in more detail in FIGS. 12-21. Several specificembodiments of such an iron are disclosed. An adapter plate for aconventional sadiron is shown in FIGS. 12-14. The heat conducting soleplate 46 is formed with a dovetail groove 42 which is adapted to closelyengage the tapered edges of sadiron 43. Because sole plate 46 is highlyheat conductive, the heat generated by sadiron 43 is adequate to providesufficient heat on bottom surface 44 of the sole plate to melt theadhesive on the seaming tape. Adapter plate 46 and sadiron 43 are formedwith a mating coupling to releasably secure them together. Theparticular coupling contemplated is a spring clamp 45, as shown in FIGS.13 and 14. The clamp is mounted to adapter plate 46 and engages a matingaccess opening in sadiron 43. By pressing down on the spring clamp thetwo elements can be disengaged.

Another embodiment of the carpet seaming iron is shown in FIGS. 15-17.Because the iron is quite wide, there may be reasons why it would bedesirable to form it in separable pieces. Thus, this embodiment isformed of right and left side elements 51 and 52, respectively. Each ofthese sadiron sides has confronting upwardly extending tabs 53 and 54 towhich are connected respective handle halves 55 and 56. A removableslide clamp 57 engages the handle halves to hold the two sections of thesadiron together during normal seaming operations. Because this iron isquite wide in order to accommodate the extra wide tape of thisinvention, under certain circumstances it is desirable to separate thetwo sections of the iron to facilitate removal of the iron from closework areas at the ends of a seam. This can easily be done by simplyslipping off the slide clamp and then lifting out one iron section at atime. It is also easier to handle and transport in the form of twosmaller segments.

A convertible carpet seaming iron is shown in FIGS. 18-21. In the closedor retracted condition of FIG. 21 sadiron 61 has a conventional widthand can be used with the normal width seaming tape. When in the open orextended condition of FIG. 20, the sole plate of sadiron 61 has a widthtwo to three times that of the normal width iron. A lever andparallelogram arrangement is employed, together with telescoping guidemembers, to permit smooth operation of this sadiron between the extendedand retracted conditions.

As shown in FIGS. 18 and 19, handle 62 is pivoted at mounting element 63by means of interconnecting pin 64. Lever arm 65 is pivoted to arm 62 bymeans of pin 71 to boss 72 adapted to slide in slot 73 of bridgingmember 74. Boss 72 is pivotably connected to parallelogram arms 75 and76 by means of pin 77. One end of arm 75 is pivotably connected to leftretractable sole plate member 81 by means of pin 82 and the other end isslidably engaged in slot 83 on right sole plate member 84 by means ofpin 85. Similarly, parallelogram arm 76 is pivotably connected to rightsole plate member 84 by means of pin 86 and opposite end pin 87slidingly engages slot 88 in sole plate member 81. Simple, telescopingguide members 91, 92, 93 and 94 ensure the parallel operation of theretractable sole plates when being moved between the retracted andextended positions.

In operation, FIGS. 18, 19 and 20 show the carpet seaming iron in theextended condition with handle 62 in its most forward position. Slidingboss 72 and sliding pins 85 and 87 are at the forward end of theirpermitted travel and the telescoping members are fully extended so thatthe sadiron is in the extended condition shown in FIG. 20. Thus, thesole plate is a combination of center sole plate 95 and side sole plates81 and 84 to provide the necessary width to heat the extended width tapeof FIG. 5. When it is desired to employ the sadiron of this embodimentfor a normal width seaming tape or to facilitate removal of the sadironat the end of a seam when the heating operation has been completed,handle 62 may be lowered to the retracted position shown as a dottedalternative in FIG. 18 and to achieve the configuration shown in FIG.21.

All three of these sole plate members have heating elements therein.They may be operated by a single switch so that they are all heated atthe same time or a switch may be operated in conjunction with themovement of handle 62 so that the left and right sole plates have powerapplied to their heating elements when in the extended position of FIG.19. The switch may be opened to remove the power to the heating elementswhen in the retracted position of FIG. 21.

In view of the above description, it is likely that improvements andmodifications will occur to those skilled in the art which are withinthe scope of the appended claims.

What is claimed is:
 1. A method for laying multiple layer, tufted carpetto substantially reduce seam peaking which tends to occur in suchcarpeting after abutting edges of the carpet are secured together bymeans of hot-melt adhesive coated normal seaming tape normally having awidth of approximately three inches and the carpet is finally stretched,said method comprising the steps of:cutting and fitting the carpet tothe floor area with two abutting carpet edges forming a carpet seam;laying a hot-melt adhesive coated enhanced width seaming tape beneathsaid carpet seam, said enhanced width seaming tape being configured withits composite modulus of elasticity varying laterally across its width,said enhanced width seaming tape having a width of approximately twicethe width of said normal seaming tape, said enhanced width seaming tapeunderlying the carpet sections substantially equally on either side ofsaid seam, there being meltable adhesive on the side of said enhancedwidth seaming tape facing upward and engaging the carpet at said carpetseam; heating the adhesive on said enhanced width seaming tape with acarpet seaming iron of a width sufficient to simultaneously heat thefull width of said enhanced width seaming tape to make the adhesivemolten; forcing the adjacent carpet edges down onto the molten adhesiveside of said enhanced width seaming tape; and then stretching the carpetto the floor periphery in conventional manner.
 2. The method recited inclaim 1, wherein said enhanced width seaming tape comprises a substrate,a layer of hot-melt adhesive and a layer of fibers known as scrimforming a predetermined pattern on said adhesive layer.
 3. The methodrecited in claim 2, wherein said scrim is so arranged on said enhancedwidth seaming tape that a central longitudinal portion of said enhancedwidth seaming tape has a first modulus of elasticity and flankinglongitudinal margin areas have a second modulus of elasticity differentfrom the first modulus.
 4. The method recited in claim 3, wherein saidsecond modulus of elasticity is less than said first modulus.
 5. Themethod recited in claim 3, wherein the width of said central portion isapproximately double the width of either said flanking margin area. 6.The method recited in claim 3, and further comprising second flankinglongitudinal margin areas having a third modulus of elasticity.
 7. Themethod recited in claim 6, wherein the third modulus of elasticity isless than the second modulus which is in turn less than the firstmodulus.
 8. The method recited in claim 3, wherein said scrim is formedwith approximately twice as many scrim fibers in said central portion asare in said flanking margin areas.
 9. The method recited in claim 8,wherein said scrim fibers are formed in a continuous lateral zig-zagpattern throughout the length of said enhanced width seaming tape. 10.The method recited in claim 8, wherein said scrim fibers are formed withone continuous zig-zag pattern in said central portion and a differentzig-zag pattern in said flanking margin areas.
 11. The method recited inclaim 8, wherein said scrim fibers are formed with one continuouszig-zag pattern in said central portion and straight, spaced fibersextending from one flanking margin area to the other.
 12. The methodrecited in claim 8, wherein said scrim fibers are formed as straightsegments of varying length arranged laterally across said enhanced widthseaming tape.
 13. A method of laying multiple layer, tufted carpet tosubstantially reduce seam peaking which tends to occur in such carpetingafter abutting edges of the carpet are secured together by means ofhot-melt adhesive coated normal seaming tape normally having a width ofapproximately three inches and the carpet is finally stretched, saidmethod resulting in a flat carpet seam and comprising the stepsof:cutting and fitting the carpet to the floor area with abutting carpetedges forming seams in conventional manner; laying a hot-melt adhesivecoated enhanced width seaming tape beneath each said carpet seam, saidenhanced width seaming tape having a width of approximately twice thewidth of said normal seaming tape and underlying the carpet sectionssubstantially equally on either side of a respective said seam, therebeing meltable adhesive on the side of said enhanced width seaming tapefacing upward and engaging the carpet at the respective said carpetseam; heating the enhanced width seaming tape with a carpet seaming ironof a width sufficient to simultaneously heat the full width of theadhesive of said enhanced width seaming tape to make the adhesivemolten; forcing the adjacent carpet edges down onto the molten adhesiveside of said enhanced width seaming tape; and then stretching the carpetto the floor periphery in conventional manner.
 14. A method of layingmultiple layer, tufted carpet to substantially reduce seam peaking whichtends to occur in such carpeting after abutting edges of the carpet aresecured together by means of hot-melt adhesive coated seaming tapenormally having a width of approximately three inches and the carpet isfinally stretched, said method resulting in a flat carpet seam andcomprising the steps of:cutting and fitting the carpet to the floor areawith abutting carpet edges forming seams in conventional manner; layinga hot-melt adhesive coated enhanced width seaming tape beneath each saidcarpet seam, said enhanced width seaming tape having a width of aboutsix inches and underlying the carpet sections substantially equally oneither side of a respective said seam, there being meltable adhesive onthe side of said enhanced width seaming tape facing upward and engagingthe carpet at the respective said carpet seam; heating the enhancedwidth seaming tape with a carpet seaming iron of a width sufficient tosimultaneously heat the full width of the adhesive of said enhancedwidth seaming tape to make the adhesive molten; forcing the adjacentcarpet edges down onto the molten adhesive side of said enhanced widthseaming tape; and then stretching the carpet to the floor periphery inconventional manner.